X波段雷达海面回波谱宽特征研究     

纪立佳  张彦敏  王运华  徐延东 《海洋学报》2019,41(7):149-158

海面电磁回波频谱宽度与海浪波高密切相关，可应用频谱宽度进行海浪有效波高反演。本文应用线性滤波法仿真出了海表散射面元在雷达视向上的投影速度，建立了回波谱宽模型，分析了雷达空间分辨率、回波时间序列长度及海洋环境参数等因素对频谱宽度的影响，同时还针对如何在实际观测过程中选择回波时间序列长度、观测方位角等参数进行了讨论。最后还将理论结果与CSIR-X波段雷达实测数据谱宽估计结果进行了比较。结果表明，剔除雷达噪声以及频率泄露的影响后，基于高斯分布标准偏差的谱宽估计方法所得结果与理论结果吻合很好，这从而证明了理论结果的可靠性。本文所得结果对海浪有效波高反演具有一定参考价值。  相似文献   

印尼贯穿流源区马鲁古海与哈马黑拉海水团来源的季节和年际变化   总被引：2，自引：1，他引：1  

王露  周磊  谢玲玲  郑全安  李强  李明明 《海洋学报(英文版)》2019,38(4):58-71

So far, large uncertainties of the Indonesian throughflow(ITF) reside in the eastern Indonesian seas, such as the Maluku Sea and the Halmahera Sea. In this study, the water sources of the Maluku Sea and the Halmahera Sea are diagnosed at seasonal and interannual timescales and at different vertical layers, using the state-of-the-art simulations of the Ocean General Circulation Model(OGCM) for Earth Simulator(OFES). Asian monsoon leaves clear seasonal footprints on the eastern Indonesian seas. Consequently, the subsurface waters(around 24.5σ_θ and at ～150 m) in both the Maluku Sea and the Halmahera Sea stem from the South Pacific(SP) during winter monsoon, but during summer monsoon the Maluku Sea is from the North Pacific(NP), and the Halmahera Sea is a mixture of waters originating from the NP and the SP. The monsoon impact decreases with depth, so that in the Maluku Sea, the intermediate water(around 26.8σ_θ and at ～480 m) is always from the northern Banda Sea and the Halmahera Sea water is mainly from the SP in winter and the Banda Sea in summer. The deep waters(around27.2σ_θ and at ～1 040 m) in both seas are from the SP, with weak seasonal variability. At the interannual timescale,the subsurface water in the Maluku Sea originates from the NP/SP during El Ni?o/La Ni?a, while the subsurface water in the Halmahera Sea always originates from the SP. Similar to the seasonal variability, the intermediate water in Maluku Sea mainly comes from the Banda Sea and the Halmahera Sea always originates from the SP. The deep waters in both seas are from the SP. Our findings are helpful for drawing a comprehensive picture of the water properties in the Indonesian seas and will contribute to a better understanding of the ocean-atmosphere interaction over the maritime continent.  相似文献   

多能互补海洋能集成发电技术研究综述     

王世明  李泽宇  于涛  马晨倍 《海洋通报》2019,38(3)

介绍了国内外基于风能、太阳能、波浪能和潮流能等海上可再生能源进行多能互补集成发电的研究发展情况,从不同技术研究侧重点、不同装置机理差异性和多能互补集成发电方式等方面进行了概括和综述,对已有设备和理论研究等进行了对比,评述了目前海洋多能互补集成发电技术研究中存在的主要问题以及未来的研究发展趋势,指出未来海洋能源集成发电需在离岸化、新材料、大型化和阵列布局等方面进行技术研究和攻关。  相似文献   

碳氮稳定同位素比值在潮间带大型底栖动物组织间差异性研究   总被引：1，自引：1，他引：0  

刘博  陈琳琳  李宝泉  侯西勇  冯光海  李晓炜  李秉钧  王玉珏 《海洋学报》2019,41(4):74-82

近年来，稳定同位素技术已被广泛应用于食物网研究中。然而，生物样品取样部位对食物网构建的影响的研究相对少见。大型底栖动物作为潮间带食物网的重要组成部分，在食物网研究中有必要对其采样部位进行统一，以增加研究结果的准确性及可比较性。本研究选取黄河三角洲和烟台潮间带10种代表性的大型底栖动物，比较δ13C和δ15N在不同采样部位中的差异。结果显示，对于大多数底栖动物而言，采样部位将直接影响到δ13C和δ15N的测定结果。当底栖动物作为摄食者，需分析其食性和营养级时，应统一采用肌肉组织，如贝类的闭壳肌或足部肌肉，蟹类的鳌足肌肉，鱼类的背部肌肉；当底栖动物作为被摄食者，需分析次级消费者的食性和营养级时，除多毛类采用去除消化道内容物的体壁外，其他种类应选取整体（难以被消化的组织除外），如贝类的软体部，蟹类肌肉与鳃等的混合组织。  相似文献   

硅灰加固宁波软土的试验研究     

王泽平  王常明  江南  张在恒 《岩土工程技术》2020,(2):111-116,121

为探索硅灰对软土的力学性质的影响,以宁波鄞州地区一种淤泥质黏土为试样,掺入不同量的硅灰,对硅灰加固土的力学性质和结构特征进行了测试。采用三轴不固结不排水剪切试验,测试分析了不同掺入量的硅灰加固土的应力应变关系,通过扫描电镜SEM照片分析了不同硅灰掺入量的硅灰加固土的结构特征。结果表明:(1)硅灰可以提高软土的黏聚力,黏聚力随着硅灰掺入量的增加而增大;(2)随着硅灰掺入量的增加,硅灰加固土的抗变形能力呈先增加后减小的趋势;(3)同一围压条件下,随着硅灰掺入量的增加,硅灰加固土的破坏偏应力逐渐增加;(4)随着硅灰掺入量的增加,硅灰加固土中大孔隙逐渐减少,小孔隙逐渐数量增加,孔径<1μm的小孔隙组分逐渐占优。  相似文献   

Tectonic nature of the NE Asian continental margin during the Late Jurassic–Early Cretaceous: constraints from the geochronology and geochemistry of igneous rocks in the NE North China Craton     

Xiao-Ming Zhang  Chen-Yang Sun  Feng Wang  Yu Li 《International Geology Review》2020,62(15):1949-1970

ABSTRACT

This paper presents geochronological, geochemical, and zircon Hf–O isotope data for late Mesozoic intrusive rocks from the northeastern North China Craton (NCC), with the aim of constraining the late Mesozoic tectonic nature of the NE Asian continental margin. U–Pb zircon data indicate that the Late Mesozoic magmatism in the northeastern NCC can be subdivided into two stages: Late Jurassic (161 ? 156 Ma) and Early Cretaceous (125 ? 120 Ma). Late Jurassic magmatism consists mainly of monzogranites. These monzogranites display high Sr/Y ratios and the tetrad effect in their REE, respectively, and have negative ε_Hf(t) values (?22.6 to ?15.8). The former indicates that the primary magma was generated by partial melting of thickened NCC lower crust, the latter suggests that the monzogranites were crystallized from highly fractionated magma, with the primary magma derived from partial melting of lower continental crust. Combined with the spatial distribution and rock associations of the Late Jurassic granitoids, we conclude that the Late Jurassic magmatism in the eastern NCC formed in a compressional environment related to oblique subduction of the Paleo-Pacific Plate beneath the Eurasia. The Early Cretaceous magmatism consists mainly of granitoids and quartz diorites. The quartz diorites formed by mixing of melts derived from the mantle and lower crust. The coeval granitoids are classified as high-K calc-alkaline and metaluminous to weakly peraluminous series. Some of the granitoids are similar to A-type granites. The granitoid ε_Hf(t) values and T_DM2 range from ?14.3 to ?1.4 and 2089 to 1274 Ma, respectively. These values indicate that their primary magma was derived from partial melting of lower crustal material of the NCC, but with a contribution of mantle-derived material. We therefore conclude that Early Cretaceous magmatism in the northeastern NCC occurred in an extensional environment related to westward subduction of the Paleo-Pacific Plate beneath Eurasia.  相似文献   

Three-dimensional finite element simulation of fracture propagation in rock specimens with pre-existing fissure(s) under compression and their strength analysis     

Ramin Pakzad  Shanyong Wang  Scott W. Sloan 《国际地质力学数值与分析法杂志》2020,44(10):1472-1494

A FORTRAN program, consistent with the commercially available finite element (FE) code ABAQUS, is developed based on a three-dimensional (3D) linear elastic brittle damage constitutive model with two damage criteria. To consider the heterogeneity of rock, the developed FORTRAN program is used to set the stiffness and strength properties of each element of the FE model following a Weibull distribution function. The reliability of the program is assessed against available experimental results for granite cylindrical specimens with a throughgoing, flat and inclined fissure. The calibration procedure of the material parameters is explained in detail, and it is shown that the compressive to tensile strength ratio can have a substantial influence on the failure response of the specimens. Numerical simulations are conducted for models with different levels of heterogeneity. The results show a smaller load bearing capacity for models with less homogeneity, representing gradual coalescence of fully damaged elements forming throughout the models during loading. The maximum load bearing capacity is studied for various combinations of inclination angles of two centrally aligned, throughgoing and flat fissures of equal length embedded in cylindrical models under uniaxial and multiaxial loading conditions. The key role of the compressive to tensile strength ratio is highlighted by repeating certain simulations with a lower compressive to tensile strength ratio. It is proven that the peak loads of the rock models with sufficiently small compressive to tensile strength ratios containing two throughgoing fissures of equal length are similar, provided that the minimum inclination angles of the models are the same. The results are presented and discussed with respect to the existing experimental findings in the literature, suggesting that the numerical model applied in this study can provide useful insight into the failure behaviour of rock-like materials.  相似文献   

东昆仑夏日哈木退变质榴辉岩地球化学、年代学特征及其地质意义     

郭峰  王盘喜  王振宁  冯乃琦 《沉积与特提斯地质》2020,40(4):45-55

本文对东昆仑夏日哈木退变质榴辉岩开展岩石地球化学和年代学研究，探讨其原岩性质和构造背景。岩石SiO₂含量为46.77%~49.31%，Al₂O₃含量为13.6%~14.6%，TiO₂含量为0.93%~2.29%，全碱（K₂O+Na₂O）含量为1.61%~2.66%，原岩属亚碱性玄武岩系列中的拉斑玄武岩。（La/Yb）_N=0.98~1.63，（La/Sm）_N=0.98~1.41，δEu=1.10~1.28，稀土元素球粒陨石标准化图呈弱Eu正异常的右倾型，岩石相对富集大离子亲石元素Rb、Ba和不相容元素U，相对亏损高场强元素Zr、Hf，Hf/Th=0.59~0.97，Th/Yb=0.13~0.27，显示其原岩具E-MORB特征。退变质榴辉岩的锆石Th/U比值为0.002~0.091，为变质成因锆石，其锆石SIMS U-Pb年龄为414.2 ±7.3 Ma，代表了退变质榴辉岩的峰变质年龄，结合区域地质背景，认为该岩石形成于早泥盆世早期由碰撞作用向碰撞后伸展作用转换的构造环境。  相似文献   

Carboniferous integrative stratigraphy and timescale of China     

Wang  Xiangdong  Hu  Keyi  Qie  Wenkun  Sheng  Qingyi  Chen  Bo  Lin  Wei  Yao  Le  Wang  Qiulai  Qi  Yuping  Chen  Jitao  Liao  Zhuoting  Song  Junjun 《中国科学:地球科学(英文版)》2019,62(1):135-153

The Carboniferous period lasted about 60 Myr, from ～358.9 Ma to ～298.9 Ma. According to the International Commission on Stratigraphy, the Carboniferous System is subdivided into two subsystems, i.e., Mississippian and Pennsylvanian, including 6 series and 7 stages. The Global Stratotype Sections and Points(GSSPs) of three stages have been ratified, the Tournaisian, Visean, and Bashkirian stages. The GSSPs of the remaining four stages(i.e., the Serpukhovian, Moscovian,Kasimovian, and Gzhelian) have not been ratified so far. This paper outlines Carboniferous stratigraphic subdivision and correlation on the basis of detailed biostratigraphy mainly from South China, and summarizes the Carboniferous chronostratigraphic framework of China. High-resolution biostratigraphic study reveals 37 conodont zones, 24 foraminiferal(including fusulinid) zones, 13 ammonoid zones, 10 brachiopod zones, and 10 rugose coral zones in the Carboniferous of China. The biostratigraphic framework based on these biozones warrants the precise correlation of regional stratigraphy of China(including2 subsystems, 4 series, and 8 stages) to that of the other regions globally. Meanwhile, the Carboniferous chemo-, sequence-,cyclo-, and event-stratigraphy of China have been intensively studied and can also be correlated worldwide. Future studies on the Carboniferous in China should focus on(1) the correlation between shallow-and deep-water facies and between marine and continental facies,(2) high-resolution astronomical cyclostratigraphy, and(3) paleoenvironment and paleoclimate analysis based on geochemical proxies such as strontium and oxygen isotopes, as well as stomatal indices of fossil plants.  相似文献   

关于确保甘肃省祁连山生态保护红线落地并严守的科技支撑建议   总被引：1，自引：0，他引：1  

王宝  王涛  王勤花  王鹏龙  徐冰鑫  高峰 《中国沙漠》2019,39(1):7-11

祁连山是中国西部重要生态安全屏障，是国家重点生态功能区，其生态保护与治理一直受到国家、地方政府和当地居民高度关注。目前，在祁连山的生态保护工作中，缺乏对现状基础数据的全面掌握，区域经济发展与生态环境保护矛盾突出，生态环境综合监测系统不完备，生态补偿机制推进实施缺乏创新。在全面梳理祁连山目前存在的重大生态问题的基础上，提出了祁连山生态保护红线落地并严守的建议，包括加快开展祁连山综合科学考察、完善并落实开展生态补偿机制、探索以正面清单为导向的协调发展模式、促进生态安全与地方经济社会可持续发展相协调、进一步实施重大配套政策、完善保障支撑体系等。  相似文献